1. Field of the Invention
The present invention relates to silo unloaders for bottom unloading type silos and more particularly to silo unloaders of the character described which employ a vertical shaft extending upwardly of a discharge opening in a silo bottom wall for supporting a plurality of flexible silage dislodging members which rotate with the shaft to dislodge the silage material.
2. Description of the Prior Art
The silo unloaders of the type adapted to be mounted in the bottom discharge opening of a silo bottom wall such as those disclosed in U.S. Pat. Nos. 3,907,131 and 3,942,656 have proven highly effective for dislodging the silage material from the lower end portion of the mass of silage contained in a silo and delivering this dislodged material at suitable feed rates through a bottom discharge opening in the bottom wall of the silo. These type of silo unloaders employ a vertical shaft which projects upwardly from support bearings which are contained in an enclosure or housing mounted in the discharge opening in the bottom wall of the silo. The shaft supports a plurality of flexible silage dislodging chains which are centrifuged outwardly to dislodge silage from the mass as the shaft is rotated. Although these silo unloaders are highly successful, a problem sometimes develops in sealing around the shaft above the supportive bearings so that water, silage and other corrosive or foreign material does not leak past the seal and come in contact with the supporting bearings causing premature bearing failure or excessive maintenance.
In prior art bottom type silage unloaders, annular seals have been formed of flexible material such as rubber but these tend to wear rapidly and have a relatively short operating life because of contact with corrosive materials and the action of the liquids developed in the silage means and the abrasive nature of some of the materials contained. Frequent replacement of the seals and bearings is often a costly and time consuming problem.
Therefore, an object of the present invention is to provide a new and improved seal for bottom type silo unloaders of the character described which seal is effective in protecting the shaft and its supporting bearings from damage because of contact with liquids, silage and other corrosive materials contained in the silos.
Another object of the present invention is to provide a new and improved bottom silo unloader.
Still another object of the present invention is to provide a new and improved bottom silo unloader requiring less maintenance and reducing the need and frequency of replacing seals and bearings.